Networks

Networks

1. LANs and WANs

   • Local Area Network
     • A LAN covers a small area such as one site or building, eg a school or a college
     • A school network is usually a LAN.
   • Wide Area Network
     • A WAN covers a large geographical area. Most WANs are made from several LANs connected together.
     • The internet is a WAN.
     • A network of bank cash dispensers is a WAN.
     • WANs can be connected together using the internet, leased lines or satellite links.
   • LANs are often connected to WANs, for example a school network could be connected to the internet.
   • ADVANTAGES
     • Sharing devices such as printers saves money.
     • Files can easily be shared between users
     • Network users can communicate by email and instant messenger.
   • DISADVANTAGES
     • Purchasing the network cabling and file servers can be expensive.
     • Managing a large network is complicated, requires training and a network manager usually needs to be employed.
     • Viruses can spread to other computers throughout a computer network.

2. TYPES OF NETWORKS

   • Bus Network
     • In a bus network all the workstations, servers and printers are joined to one cable (the bus). At each end of the cable a terminator is fitted to stop signals reflecting back down the bus.
     • ADVANTAGES
       • it is easy to install
       • it is cheap to install, as it doesn't require much cable
     • DISADVANTAGES
       • if the main cable fails or gets damaged the whole network will fail
       • as more workstations are connected the performance of the network will become slower because of data collisions
       • every workstation on the network "sees" all of the data on the network – this is a security risk